Bad cap outcomes

[D Yuniskis]

Hi,

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis". Particularly, PC's.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)? Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present? How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don

 

[N_Cook]

D Yuniskis <not.going.to.be@seen.com> wrote in message
news:ig4qkb$paa$1@speranza.aioe.org...

Hi,

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis". Particularly, PC's.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)? Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present? How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don

And what percentage of times do you introduce new problems of disrupted
multi-layer board traces/vias in the act of desoldering/soldering caps ?

 

[Jeffrey Angus]

On 1/6/2011 10:36 AM, N_Cook wrote:

D Yuniskis<not.going.to.be@seen.com> wrote:
E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don


And what percentage of times do you introduce new problems of disrupted
multi-layer board traces/vias in the act of desoldering/soldering caps ?

Well obviously, using something a bit more suitable
than a Weller soldering gun to do the re-cap helps.

But yeah, I did mine, because I bought a pair of
dells with the cap-itis problems for $50. With $25
worth of caps they're good as new.

Would I do this for a commercial customer? No, I'd
give him $25 for the old machine and have him buy a
new one.

Then fix his old one for myself. ;-)

Jeff

 

[Baron]

D Yuniskis Inscribed thus:

Hi,

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis". Particularly, PC's.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)? Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present? How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don

Its really a matter of horses for courses. Some you do and some you
don't ! I don't recall having further trouble with re-capped PC
mainboards. Having said that not all clients will come back and
complain if the machine fails soon after its been repaired. Its become
to easy to replace rather than repair nowadays !

--
Best Regards:
Baron.

 

[D Yuniskis]

On 1/6/2011 9:42 AM, Jeffrey Angus wrote:

On 1/6/2011 10:36 AM, N_Cook wrote:
D Yuniskis<not.going.to.be@seen.com> wrote:
E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

And what percentage of times do you introduce new problems of disrupted
multi-layer board traces/vias in the act of desoldering/soldering caps ?

Well obviously, using something a bit more suitable
than a Weller soldering gun to do the re-cap helps.

But yeah, I did mine, because I bought a pair of
dells with the cap-itis problems for $50. With $25
worth of caps they're good as new.

Would I do this for a commercial customer? No, I'd
give him $25 for the old machine and have him buy a
new one.

Assuming the old one is *worth* $25... :>

Then fix his old one for myself. ;-)

That's my point. If it's something you are going to
use yourself it's a different case -- if you later
see it "acting up", you can shrug your shoulders and
give it the old "heave-ho". OTOH, you wouldn't want to
"do your books" on it... :-/

But, the question still stands: did you *examine*
what was actually happening on the board or just
"blindly" replace all the caps and hope for the best?

 

[Jeffrey Angus]

On 1/6/2011 11:00 AM, D Yuniskis wrote:

Assuming the old one is *worth* $25... :

he customer "good will" is worth the $25, and if
I get something functional in the process, that's
just a bonus.

But, the question still stands: did you *examine*
what was actually happening on the board or just
"blindly" replace all the caps and hope for the best?

You mean poke around with a scope, looking at waveforms,
measuring supply rails and such? No, not worth the time.

It's in the same category with trying to rejuvenate
SLA batteries. ;-) I did do a cursory check and if I
see just one suspect cap, they all get replaced.

99.99% of the time, that IS the problem, so I just
go with that, if the board goes up in smoke, well,
no big deal, I'm out a bit of time and material AND
it didn't do it in a customer's work place.

Jeff

 

[Meat Plow]

On Thu, 06 Jan 2011 09:38:53 -0700, D Yuniskis wrote:

Hi,

I'm wondering what the prevailing approach is when it comes to dealing
with kit that has been found to have "bad cap-itis". Particularly,
PC's.

Do folks exploe the current operating conditions of the machine *before*
re-cap-ping (i.e., see what supplies are affected, what sorts of ripple
is present, etc.)? Or, do you just replace and *functionally* retest
(i.e., if you haven't probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at that level of detail seems
to be a contradiction)?

In particular, how do you know if the system has been operating within
"absolute maximum ratings" while this fault has been present? How do
you know the system's reliability/integrity hasn't been compromised (so
your "fix" is just a band-aid)?

E.g., I've been recommending disposing of machines with this problem.
The labor to re-cap just doesn't make sense given the book value of
machines that exhibit these problems -- especially in light of the fact
that you can't be sure that the "repaired" machine is really "100%"
(maybe OK for a machine you use informally at home, but would you want
to *rely* on it in a commercial environment?).

I suspect most machines are just recapped and re-used but wanted
confirmation or repudiation of that opinion.

Thanks!
--don

Most mainboards are disposable. Better boards are made with better
components and cost considerably more. Sure you can buy a new
board for an Intel i5 or AMD PhenomII for under $40 but don't expect
longevity. My quad core Asus M4A78T-E board hast this feature:

100% All High-Quality Conductive Polymer Capacitors.
5000hrs VRM, over 57 years’ operation lifespan at 65c.

A look at the board shows none of the old style shrink-wrapped cans.

Cost of the mainboard + AMD PhenomII 955 quad 3.2ghz bundle was $300.
So it's not toss away stuff.

--
Live Fast, Die Young and Leave a Pretty Corpse

 

[Cydrome Leader]

D Yuniskis <not.going.to.be@seen.com> wrote:

On 1/6/2011 9:42 AM, Jeffrey Angus wrote:
On 1/6/2011 10:36 AM, N_Cook wrote:
D Yuniskis<not.going.to.be@seen.com> wrote:
E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

And what percentage of times do you introduce new problems of disrupted
multi-layer board traces/vias in the act of desoldering/soldering caps ?

Well obviously, using something a bit more suitable
than a Weller soldering gun to do the re-cap helps.

But yeah, I did mine, because I bought a pair of
dells with the cap-itis problems for $50. With $25
worth of caps they're good as new.

Would I do this for a commercial customer? No, I'd
give him $25 for the old machine and have him buy a
new one.

Assuming the old one is *worth* $25... :

Then fix his old one for myself. ;-)

That's my point. If it's something you are going to
use yourself it's a different case -- if you later
see it "acting up", you can shrug your shoulders and
give it the old "heave-ho". OTOH, you wouldn't want to
"do your books" on it... :-/

But, the question still stands: did you *examine*
what was actually happening on the board or just
"blindly" replace all the caps and hope for the best?

I have a heap of IBM workstations that "need" new caps.

the issues though as mentioned, is do I want to waste the time to
resurrect a 600 MHz desktop with windows 2000. Even if the computers
worked they'd still probably just be sitting in a pile anyways.

 

[Michael A. Terrell]

D Yuniskis wrote:

On 1/6/2011 9:42 AM, Jeffrey Angus wrote:
? On 1/6/2011 10:36 AM, N_Cook wrote:
?? D Yuniskis?not.going.to.be@seen.com? wrote:
??? E.g., I've been recommending disposing of machines
??? with this problem. The labor to re-cap just doesn't
??? make sense given the book value of machines that
??? exhibit these problems -- especially in light of
??? the fact that you can't be sure that the "repaired"
??? machine is really "100%" (maybe OK for a machine you
??? use informally at home, but would you want to *rely*
??? on it in a commercial environment?).
???
??? I suspect most machines are just recapped and re-used
??? but wanted confirmation or repudiation of that opinion.
??
?? And what percentage of times do you introduce new problems of disrupted
?? multi-layer board traces/vias in the act of desoldering/soldering caps ?
?
? Well obviously, using something a bit more suitable
? than a Weller soldering gun to do the re-cap helps.
?
? But yeah, I did mine, because I bought a pair of
? dells with the cap-itis problems for $50. With $25
? worth of caps they're good as new.
?
? Would I do this for a commercial customer? No, I'd
? give him $25 for the old machine and have him buy a
? new one.

Assuming the old one is *worth* $25... :?

? Then fix his old one for myself. ;-)

That's my point. If it's something you are going to
use yourself it's a different case -- if you later
see it "acting up", you can shrug your shoulders and
give it the old "heave-ho". OTOH, you wouldn't want to
"do your books" on it... :-/

But, the question still stands: did you *examine*
what was actually happening on the board or just
"blindly" replace all the caps and hope for the best?

What happens is that a lot of motherboards were built with crap
electrolytics. They have a LOT of ripple current flowing through them,
which makes them run warm. When the electrolyte starts to dry out the
heating gets worse, till the caps fail. If you use a good grade of low
ESR 105 degree caps like the Panasonic FM series you end up with a
better than original motherboard.


--
What are you looking for, all the way down here?

 

[Michael A. Terrell]

N_Cook wrote:

And what percentage of times do you introduce new problems of disrupted
multi-layer board traces/vias in the act of desoldering/soldering caps ?

0%, if you know what the hell you are doing, and have decent tools.


--
What are you looking for, all the way down here?

 

On Jan 6, 8:50 am, Baron <baron.nos...@linuxmaniac.nospam.net> wrote:

D Yuniskis Inscribed thus:





Hi,

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis".  Particularly, PC's.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)?  Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present?  How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

E.g., I've been recommending disposing of machines
with this problem.  The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don

Its really a matter of horses for courses.  Some you do and some you
don't !  I don't recall having further trouble with re-capped PC
mainboards.  Having said that not all clients will come back and
complain if the machine fails soon after its been repaired.  Its become
to easy to replace rather than repair nowadays !

--
Best Regards:
                     Baron.

Had a PC mobo at work a couple years back that was not available any
longer but required as part of an expensive system. Replacing the bad
caps (and they were REALLY bad) has kept it working fine for 2 years.
Get a GOOD soldering iron like a Metcal. An inexpensive ESR meter is a
must. There are sometimes small ceramics in parallel with 'lytics and
these will 'fake out' the ESR meter. If a 'lytic measures bad, it's
bad but if it measures good, it may still be bad while measured in
circuit. Warming the cap while unsoldering it will make it read better
on the meter but very often gets much worse after cooling off. There
are some places where the caps need to be nearly perfect. A favorite
critical place is the filter in a SMPS on the 3.3 or 5V rail. The cap
may read 'OK' but that may not be nearly good enough. Don't use crap
grade caps either. For SM caps I like Panasonic FK or FP caps. Through
hole I start wit Panasonic FM, Nichicon HM.HN, HZ, PW and other low
ESR caps. Look for highest ripple current ratings.

Often there are a lot of caps same value and manufacturer. If some
read bad and others good, I change all of them since it's only a
matter of time for the rest to fail.

G˛

 

[Baron]

stratus46@yahoo.com Inscribed thus:

On Jan 6, 8:50 am, Baron <baron.nos...@linuxmaniac.nospam.net> wrote:
D Yuniskis Inscribed thus:





Hi,

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis".  Particularly, PC's.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)?  Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present?  How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

E.g., I've been recommending disposing of machines
with this problem.  The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

Thanks!
--don

Its really a matter of horses for courses.  Some you do and some you
don't !  I don't recall having further trouble with re-capped PC
mainboards.  Having said that not all clients will come back and
complain if the machine fails soon after its been repaired.  Its
become to easy to replace rather than repair nowadays !

--
Best Regards:
Baron.

Had a PC mobo at work a couple years back that was not available any
longer but required as part of an expensive system. Replacing the bad
caps (and they were REALLY bad) has kept it working fine for 2 years.
Get a GOOD soldering iron like a Metcal. An inexpensive ESR meter is a
must. There are sometimes small ceramics in parallel with

I've seen some of those that ended up being just two wires stuck out of
the PCB.

'lytics and
these will 'fake out' the ESR meter. If a 'lytic measures bad, it's
bad but if it measures good, it may still be bad while measured in
circuit. Warming the cap while unsoldering it will make it read better
on the meter but very often gets much worse after cooling off. There
are some places where the caps need to be nearly perfect. A favorite
critical place is the filter in a SMPS on the 3.3 or 5V rail. The cap
may read 'OK' but that may not be nearly good enough. Don't use crap
grade caps either. For SM caps I like Panasonic FK or FP caps. Through
hole I start wit Panasonic FM, Nichicon HM.HN, HZ, PW and other low
ESR caps. Look for highest ripple current ratings.

I agree ! The only comment that I would add is be carful of physical
size and lead spacing. I've been caught out by slightly larger
diameter and hight restraints. In particular intel boards where there
have been 6 or more caps arranged tight side by side.

Often there are a lot of caps same value and manufacturer. If some
read bad and others good, I change all of them since it's only a
matter of time for the rest to fail.

G²

Yes I agree ! I've also found that the caps in the RAM PSU circuits go
bad in the same way. Very often, particularly on newer boards the RAM
has its own dedicated PSU. The caps are much smaller both physically
and in value, but also go high ESR causing some very strange behavior.

--
Best Regards:
Baron.

 

[Jeff Liebermann]

On Thu, 06 Jan 2011 09:38:53 -0700, D Yuniskis
<not.going.to.be@seen.com> wrote:

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis". Particularly, PC's.

That's rapidly becoming a major part of my business, second only to
malware removal.

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)?

No. It takes too much time. If it's obvious that there are bad caps
in the box, the only decision is whether to replace ALL the caps, not
probing around looking for sections to avoid. Where I get into
trouble is when I get a working machine, that has obvious signs of
leaking or bulging caps, that will eventually die. The customer often
does not want me to do a major motherboard capacitor replacement if
it's still working. Oddly, some of these machines have lasted years
with obvious bulging caps.

Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

No. I use the shotgun approach and just replace every cap of the same
type. The time I spend doing the "extra" caps is about the same as
what it would take to probe around looking for the worst offenders.
The idea is to do the job once, and not have it come back with
additional blown caps.

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present? How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

Ouch. I've bought bulk caps on eBay suspecting that I may be asking
for trouble by installing garbage caps. When possible, I'll buy
Panasonic caps because I've had no problems with them. If it will
fit, I try to increase the voltage rating, even if it means using a
smaller capacitance value. I have attempted some accelerated lifetime
testing using an ESR meter, with inconclusive results. At this time,
I can't tell the difference between a new bad cap, and new good cap. I
consider uprating the caps near the CPU as mandatory as I know (and
have measured and calculated) that they are running too hot for their
voltage rating. Also, I try to use polymer caps, but they're only
available in smaller values and kinda expensive.

E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

Not totally true. The problem with getting a new machine is that the
customer will have to pay me to transplant their software to the new
machine. Often, that's more expensive than the machine. If it
involves an OS upgrade, it gets more complicated. Of course if the
machine is ancient, it's not an issue.

There's little difference between home and "commercial" machines these
days unless you're talking about servers. Well, maybe more chrome and
glitz on the home machines.

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

It's about 50% here. If the machine is more than about 6 years old,
I'll usually suggest a replacement. If fairly recent (Core2Duo or
better), I fix it. My recent batting average is about 75% success. It
was much worse in the past when I didn't replace all the caps.

However, a major problem has been BGA array soldering. If I dive into
the machine, replace all the caps, there are still plenty of other
things that can cause a subsequent warranty problem. I try to warn
the customer that replacing the caps is a "best effort" and that if it
fails, they're committed to buying a new machine, and that I owe them
a new machine. It's awkward, messy, and full of problems. They have
to recognize that recapping involved some risk. It's often easier to
just suggest they buy a new machine than to deal with the ethical
issues required to convince them that simply touching their machine
does not create a lifetime warranty.
<http://802.11junk.com/jeffl/pics/drivel/slides/diploma.html>
This is from about 1987.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Baron]

Jeff Liebermann Inscribed thus:

On Thu, 06 Jan 2011 09:38:53 -0700, D Yuniskis
not.going.to.be@seen.com> wrote:

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis". Particularly, PC's.

That's rapidly becoming a major part of my business, second only to
malware removal.

Agreed ! Malware is most definitely No:1 Bad caps No:2 !

Do folks exploe the current operating conditions
of the machine *before* re-cap-ping (i.e., see
what supplies are affected, what sorts of ripple
is present, etc.)?

No. It takes too much time. If it's obvious that there are bad caps
in the box, the only decision is whether to replace ALL the caps, not
probing around looking for sections to avoid. Where I get into
trouble is when I get a working machine, that has obvious signs of
leaking or bulging caps, that will eventually die. The customer often
does not want me to do a major motherboard capacitor replacement if
it's still working. Oddly, some of these machines have lasted years
with obvious bulging caps.

I tend to point out to the customer that there is a liability in leaving
bad caps alone. At some point there will be a catastrophic failure and
that they will have to pay again at some time in the future. Since
they are paying a fixed service charge its in their interests to have
the caps replaced before that happens. Yes it bumps up the bill, but
not as much as it would if they have to replace the machine before they
need to !

Or, do you just replace and
*functionally* retest (i.e., if you haven't
probed the circuit to get an idea for the exact
nature of the problem, probing afterwards at
that level of detail seems to be a contradiction)?

No. I use the shotgun approach and just replace every cap of the same
type. The time I spend doing the "extra" caps is about the same as
what it would take to probe around looking for the worst offenders.
The idea is to do the job once, and not have it come back with
additional blown caps.

I would do the same. I have also started paying attention to the caps
in the RAM PSU circuits and replacing them as well. Having had some
really weird machine behavior because they have become bad.

In particular, how do you know if the system has
been operating within "absolute maximum ratings"
while this fault has been present? How do you
know the system's reliability/integrity hasn't
been compromised (so your "fix" is just a
band-aid)?

Ouch. I've bought bulk caps on eBay suspecting that I may be asking
for trouble by installing garbage caps. When possible, I'll buy
Panasonic caps because I've had no problems with them. If it will
fit, I try to increase the voltage rating, even if it means using a
smaller capacitance value. I have attempted some accelerated lifetime
testing using an ESR meter, with inconclusive results. At this time,
I can't tell the difference between a new bad cap, and new good cap. I
consider uprating the caps near the CPU as mandatory as I know (and
have measured and calculated) that they are running too hot for their
voltage rating. Also, I try to use polymer caps, but they're only
available in smaller values and kinda expensive.

I've had some very odd behavior that has disappeared when replacing caps
not directly involved with the CPU PSU circuits. I recall one machine
that had a very odd patterning on the screen as the resolution was
increased. Replacing the RAM PSU caps cured that problem. The clue
was only the on board graphics showed the problem. Putting in an
external graphics card was just fine.

E.g., I've been recommending disposing of machines
with this problem. The labor to re-cap just doesn't
make sense given the book value of machines that
exhibit these problems -- especially in light of
the fact that you can't be sure that the "repaired"
machine is really "100%" (maybe OK for a machine you
use informally at home, but would you want to *rely*
on it in a commercial environment?).

Not totally true. The problem with getting a new machine is that the
customer will have to pay me to transplant their software to the new
machine. Often, that's more expensive than the machine. If it
involves an OS upgrade, it gets more complicated. Of course if the
machine is ancient, it's not an issue.

There's little difference between home and "commercial" machines these
days unless you're talking about servers. Well, maybe more chrome and
glitz on the home machines.

Very true nowadays.

I suspect most machines are just recapped and re-used
but wanted confirmation or repudiation of that opinion.

It's about 50% here. If the machine is more than about 6 years old,
I'll usually suggest a replacement. If fairly recent (Core2Duo or
better), I fix it. My recent batting average is about 75% success. It
was much worse in the past when I didn't replace all the caps.

However, a major problem has been BGA array soldering. If I dive into
the machine, replace all the caps, there are still plenty of other
things that can cause a subsequent warranty problem. I try to warn
the customer that replacing the caps is a "best effort" and that if it
fails, they're committed to buying a new machine, and that I owe them
a new machine. It's awkward, messy, and full of problems. They have
to recognize that recapping involved some risk. It's often easier to
just suggest they buy a new machine than to deal with the ethical
issues required to convince them that simply touching their machine
does not create a lifetime warranty.

Yes that can be a problem with some clients. They expect you to be fair
with them, but they aren't prepared to be fair with you.

I've actually had an instance where a client sued me and the Judge found
in my favor. They then refused to abide by the judgement, so I counter
sued and won. They still refused to accept that they had to pay and
ended up with the court bailiff paying them a visit. I'm currently
getting ÂŁ2.00p per week and expect to wait about twelve years before I
get paid in full.

http://802.11junk.com/jeffl/pics/drivel/slides/diploma.html
This is from about 1987.

Hey Jeff, can I use that ! Big Grin.

--
Best Regards:
Baron.

 

[whit3rd]

On Jan 6, 8:38 am, D Yuniskis <not.going.to...@seen.com> wrote:

I'm wondering what the prevailing approach is when
it comes to dealing with kit that has been found to
have "bad cap-itis".  Particularly, PC's.

I suspect most machines are just recapped and re-used

Firstly, the reason for 'bad caps' could be (1) faulty
chemistry of a batch at the factory, (2) substandard
or counterfeit products, (3) poor design.

For the 2002-2005 period, there was lots of (1) and (2)
going on. If that's the issue, you have to replace all
the high-ripple-current capacitors at the same time (and
it might not be terribly difficult to do so). The ones that
haven't failed, are VERY LIKELY to die soon.

I've never had all the right sizes and ratings of capacitors
handy in my stock, so it takes a week or so to order
replacements (and a half hour or more to compose an
online order of the dozen different types for a board).
Mainly, if this were a work machine, it'd be too
slow getting it back to the customer, so "time to upgrade"
is the rule. If it's for a spare/backup computer, or other
low-time-pressure situation, sure, I'd recap. Have
done a few, in fact, just here at home (four DTV boxes
and a computer or two).

Warning: if the motherboard caps failed, check also the power
supply (same time-of-manufacture, after all).

 

[Jeff Liebermann]

On Fri, 07 Jan 2011 20:23:19 +0000, Baron
<baron.nospam@linuxmaniac.nospam.net> wrote:

http://802.11junk.com/jeffl/pics/drivel/slides/diploma.html
This is from about 1987.

Hey Jeff, can I use that ! Big Grin.

Sure. Unfortunately, the "Certificate Maker" program I used to create
it only ran on a Mac Plus on System 6. I still have the program
somewhere, but the Mac got turned into a fishbowl after it blew up its
third or fourth flyback xformer. Feel free to use the JPG. If you
want a better scan, I have the original framed and hanging above my
desk where the customer can't miss seeing it. I have yet to find a
modern program that made stock certificate borders as nice as the
original 1987 Mac program.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com jeffl@cruzio.com
# http://www.LearnByDestroying.com AE6KS

 

[Baron]

Jeff Liebermann Inscribed thus:

On Fri, 07 Jan 2011 20:23:19 +0000, Baron
baron.nospam@linuxmaniac.nospam.net> wrote:

http://802.11junk.com/jeffl/pics/drivel/slides/diploma.html
This is from about 1987.

Hey Jeff, can I use that ! Big Grin.

Sure. Unfortunately, the "Certificate Maker" program I used to create
it only ran on a Mac Plus on System 6. I still have the program
somewhere, but the Mac got turned into a fishbowl after it blew up its
third or fourth flyback xformer. Feel free to use the JPG. If you
want a better scan, I have the original framed and hanging above my
desk where the customer can't miss seeing it. I have yet to find a
modern program that made stock certificate borders as nice as the
original 1987 Mac program.

They say great minds think alike. That is exactly what I had in mind.
A nice framed print, conspicuously placed.
I think its great ! (*)
Thank you:

--
Best Regards:
Baron.